Absorption refrigerators have been commonly used in e.g. recreation vehicles and mobile homes for a long time. More recently, so called side-by-side absorption refrigerators have been increasingly popular also in such mobile applications. In side-by-side refrigerators a freezing compartment and a food storage compartment, which is kept at a higher temperature, are arranged vertically side by side and separated by a vertical partition wall. The evaporator tube is normally arranged in or at the rear wall of the refrigerator cabinet. The evaporator has a first freezer section, which extends in or at an interior surface of a portion of the rear wall, which portion covers the freezer. A second downstream section of the evaporator is arranged to cool the higher temperature compartment and extends in or at an interior surface of a portion of the rear wall, which portion covers the higher temperature compartment.
A problem with this type of absorption refrigerator cabinets is a considerable heat transfer through the rear wall from the outside of the cabinet to the inside. Such inwardly directed heat transfer is driven by the difference in temperatures between the outside and the inside of the cabinet. Therefore, the heat transfer through the surrounding walls is particularly high into the freezer compartment. The freezer section of the evaporator is the coldest section of the evaporator. Since the freezer section is arranged in or at the rear wall of the freezer compartment, this freezer rear wall will have the lowest temperature of all the walls surrounding the refrigerator cabinet. Thus, the difference in temperature between the surrounding atmosphere and the inside of the cabinet walls is greatest at the rear freezer wall. Therefore, heat transfer into the cabinet is also greatest through the rear wall of the freezer compartment, near to the freezer section of the evaporator.
Heat transfer into the refrigerator cabinet is particularly disadvantageous at absorption refrigerators used in mobile applications. At absorption refrigerators, the physical dimensions of the refrigeration system limit the maximum cooling capacity. This makes it difficult to keep the respective compartments at the desired temperature. This problem is particularly severe for the freezer compartment, for which, at modern mobile refrigerators, it is desired to keep the temperature as low as −18° C. Any heat which is added into the cabinet is therefore most undesirable and often causes the temperature in the freezer to raise above the desired value. This in turn deteriorates the quality of foodstuff stored in the freezer or reduces the maximum possible storage time.
A further problem with the above-described known refrigerator is that the time required for lowering the freezer temperature from the starting temperature to the desired freezer temperature at start up of the system (so called “pull-down”) is relatively long. This is partly caused by the fact that the freezer section of the evaporator is arranged in or at one of the outer walls of the cabinet. The insulation inside the outer walls has to be comparatively thick and it contains a considerable amount of heat, which is absorbed by the evaporator during the initial temperature reduction in the freezer compartment. Considerable cooling capacity of the refrigeration system is thus used for absorbing heat from the outer wall instead of the air inside the freezer compartment, whereby the pull-down time is extended.